The Taoiseach and the British Prime Minister, Mr Blair, are expected to join intensive negotiations in Belfast this week in an attempt to break the deadlock on decommissioning and set up an executive by the June 30th deadline.
Both leaders are understood to have cleared their diaries, and sources said they were most likely to visit the North on Thursday. President Clinton said yesterday that he would do everything possible to help end the stalemate.
A Downing Street spokesman said: "The President said he was ready day and night to do what he could but they both recognised that at the end of the day it must be the parties that take the process forward."
The Northern Secretary, Dr Mo Mowlam, will hold talks with the Minister for Foreign Affairs, Mr Andrews, in Dublin today. Dr Mowlam told BBC's Breakfast With Frost yesterday that there was a danger of the political process unravelling if agreement was not reached this month. "If we go past the 30th, into Drumcree, into a long summer, a lot of the good work could well be unpicked," she said.
Decommissioning was not a precondition for Sinn Fein taking its two cabinet seats but it was an obligation under the Belfast Agreement, she said. "It's got to start at some point and the real problem is which step is being taken first. It's about trust, it's about confidence, it's about believing, `If you move, I'm going to move and we have both to move to make it work'. "
She believed decommissioning could happen at any time, but it might be possible that if the executive was formed first, the paramilitaries would have the "necessary confidence" to fulfil their duty to hand over arms.
Dr Mowlam said "low-level violence" was taking place in the North and she was keeping the Provisional IRA and loyalist cease-fires under review. But she would not be rushed into making any judgments about them.
The North's Political Development Minister, Mr Paul Murphy, will hold preparatory talks with the parties over the next three days. Mr Blair insisted yesterday that the issue of weapons could not be dodged.
"People in this executive can't be expected to sit down with others unless they are sure they are only committed to exclusively peaceful means. That is why decommissioning is a part of this process and we can get through it but we can't get round it.
"It does have to happen and people have got to recognise their duty to make it happen. It should happen now."
Asked whether he was hopeful that the matter would be resolved, Mr Blair said: "I don't know. I think it is very difficult indeed. It is very frustrating for the people of Northern Ireland because all the big questions have been resolved."
In a statement at the weekend, Sinn Fein accused the UUP of trying to "blackmail and block" progress on the executive. "In the context of the overall implementation of the Good Friday agreement, what the Ulster Unionists are demanding is that Sinn Fein alone must deliver decommissioning while the agreement itself is not implemented.
"Their position is clearly in breach of the agreement signed in good faith by all the parties. Of those nine parties who signed the Good Friday agreement, the UUP is the only one not backing its full implementation."
Speaking on GMTV yesterday the Sinn Fein senior negotiator, Mr Martin McGuinness, said "rejectionist" elements within unionism could destroy the agreement. "Don't fool yourself that it is about the issue of decommissioning. It's about more than that. It's because they don't want to see a Fenian in government.
"It has been made very clear to all the political parties that if powers are not devolved to the North of Ireland by June 30th, then I think that the deadline is absolute and I think we will see, first of all, the fall of the executive.
"I think, clearly, if there is no devolution of power and no move forward by everyone together, at least on the pro-agreement side, that the Assembly will fall on June 30th." However, Mr McGuinness was still confident that agreement could be reached over the next nine days.
The UUP deputy leader, Mr John Taylor, said he was pessimistic about the chances of a breakthrough on decommissioning. On BBC Radio Ulster's Inside Politics, he said he believed the Provisionals would not give up their weapons. The Belfast Agreement would not work unless the SDLP "get off the fence and decide if they are going to back those dedicated to democracy and peaceful methods or those who still want to maintain a private, illegal army."